agent_panel: Refine git pickers design in the empty thread view (#53324)

Follow-up to https://github.com/zed-industries/zed/pull/52979 with some
design refinements.

Release Notes:

- N/A

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Co-authored-by: cameron <cameron.studdstreet@gmail.com>
Co-authored-by: Anthony Eid <hello@anthonyeid.me>
eb78326569Danilo Leal committed on 4/7/2026, 5:41:11 PM· committed by GitHubparent082950d
8 files changedLine totals unavailable